/*
 * jcphuff.c
 *
 * Copyright (C) 1995, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains Huffman entropy encoding routines for progressive JPEG.
 *
 * We do not support output suspension in this module, since the library
 * currently does not allow multiple-scan files to be written with output
 * suspension.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
#include "jchuff.h"				/* Declarations shared with jchuff.c */

#ifdef C_PROGRESSIVE_SUPPORTED

/* Expanded entropy encoder object for progressive Huffman encoding. */

typedef struct
{
	struct jpeg_entropy_encoder pub;	/* public fields */

	/* Mode flag: TRUE for optimization, FALSE for actual data output */
	boolean         gather_statistics;

	/* Bit-level coding status.
	 * next_output_byte/free_in_buffer are local copies of cinfo->dest fields.
	 */
	JOCTET         *next_output_byte;	/* => next byte to write in buffer */
	size_t          free_in_buffer;	/* # of byte spaces remaining in buffer */
	INT32           put_buffer;	/* current bit-accumulation buffer */
	int             put_bits;	/* # of bits now in it */
	j_compress_ptr  cinfo;		/* link to cinfo (needed for dump_buffer) */

	/* Coding status for DC components */
	int             last_dc_val[MAX_COMPS_IN_SCAN];	/* last DC coef for each component */

	/* Coding status for AC components */
	int             ac_tbl_no;	/* the table number of the single component */
	unsigned int    EOBRUN;		/* run length of EOBs */
	unsigned int    BE;			/* # of buffered correction bits before MCU */
	char           *bit_buffer;	/* buffer for correction bits (1 per char) */
	/* packing correction bits tightly would save some space but cost time... */

	unsigned int    restarts_to_go;	/* MCUs left in this restart interval */
	int             next_restart_num;	/* next restart number to write (0-7) */

	/* Pointers to derived tables (these workspaces have image lifespan).
	 * Since any one scan codes only DC or only AC, we only need one set
	 * of tables, not one for DC and one for AC.
	 */
	c_derived_tbl  *derived_tbls[NUM_HUFF_TBLS];

	/* Statistics tables for optimization; again, one set is enough */
	long           *count_ptrs[NUM_HUFF_TBLS];
} phuff_entropy_encoder;

typedef phuff_entropy_encoder *phuff_entropy_ptr;

/* MAX_CORR_BITS is the number of bits the AC refinement correction-bit
 * buffer can hold.  Larger sizes may slightly improve compression, but
 * 1000 is already well into the realm of overkill.
 * The minimum safe size is 64 bits.
 */

#define MAX_CORR_BITS  1000		/* Max # of correction bits I can buffer */

/* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than INT32.
 * We assume that int right shift is unsigned if INT32 right shift is,
 * which should be safe.
 */

#ifdef RIGHT_SHIFT_IS_UNSIGNED
#define ISHIFT_TEMPS	int ishift_temp;
#define IRIGHT_SHIFT(x,shft)  \
	((ishift_temp = (x)) < 0 ? \
	 (ishift_temp >> (shft)) | ((~0) << (16-(shft))) : \
	 (ishift_temp >> (shft)))
#else
#define ISHIFT_TEMPS
#define IRIGHT_SHIFT(x,shft)	((x) >> (shft))
#endif

/* Forward declarations */
METHODDEF boolean encode_mcu_DC_first JPP((j_compress_ptr cinfo, JBLOCKROW * MCU_data));
METHODDEF boolean encode_mcu_AC_first JPP((j_compress_ptr cinfo, JBLOCKROW * MCU_data));
METHODDEF boolean encode_mcu_DC_refine JPP((j_compress_ptr cinfo, JBLOCKROW * MCU_data));
METHODDEF boolean encode_mcu_AC_refine JPP((j_compress_ptr cinfo, JBLOCKROW * MCU_data));
METHODDEF void finish_pass_phuff JPP((j_compress_ptr cinfo));
METHODDEF void finish_pass_gather_phuff JPP((j_compress_ptr cinfo));


/*
 * Initialize for a Huffman-compressed scan using progressive JPEG.
 */

METHODDEF void start_pass_phuff(j_compress_ptr cinfo, boolean gather_statistics)
{
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	boolean         is_DC_band;
	int             ci, tbl;
	jpeg_component_info *compptr;

	entropy->cinfo = cinfo;
	entropy->gather_statistics = gather_statistics;

	is_DC_band = (cinfo->Ss == 0);

	/* We assume jcmaster.c already validated the scan parameters. */

	/* Select execution routines */
	if(cinfo->Ah == 0)
	{
		if(is_DC_band)
			entropy->pub.encode_mcu = encode_mcu_DC_first;
		else
			entropy->pub.encode_mcu = encode_mcu_AC_first;
	}
	else
	{
		if(is_DC_band)
			entropy->pub.encode_mcu = encode_mcu_DC_refine;
		else
		{
			entropy->pub.encode_mcu = encode_mcu_AC_refine;
			/* AC refinement needs a correction bit buffer */
			if(entropy->bit_buffer == NULL)
				entropy->bit_buffer = (char *)
					(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, MAX_CORR_BITS * SIZEOF(char));
		}
	}
	if(gather_statistics)
		entropy->pub.finish_pass = finish_pass_gather_phuff;
	else
		entropy->pub.finish_pass = finish_pass_phuff;

	/* Only DC coefficients may be interleaved, so cinfo->comps_in_scan = 1
	 * for AC coefficients.
	 */
	for(ci = 0; ci < cinfo->comps_in_scan; ci++)
	{
		compptr = cinfo->cur_comp_info[ci];
		/* Initialize DC predictions to 0 */
		entropy->last_dc_val[ci] = 0;
		/* Make sure requested tables are present */
		/* (In gather mode, tables need not be allocated yet) */
		if(is_DC_band)
		{
			if(cinfo->Ah != 0)	/* DC refinement needs no table */
				continue;
			tbl = compptr->dc_tbl_no;
			if(tbl < 0 || tbl >= NUM_HUFF_TBLS || (cinfo->dc_huff_tbl_ptrs[tbl] == NULL && !gather_statistics))
				ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl);
		}
		else
		{
			entropy->ac_tbl_no = tbl = compptr->ac_tbl_no;
			if(tbl < 0 || tbl >= NUM_HUFF_TBLS || (cinfo->ac_huff_tbl_ptrs[tbl] == NULL && !gather_statistics))
				ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl);
		}
		if(gather_statistics)
		{
			/* Allocate and zero the statistics tables */
			/* Note that jpeg_gen_optimal_table expects 257 entries in each table! */
			if(entropy->count_ptrs[tbl] == NULL)
				entropy->count_ptrs[tbl] = (long *)
					(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 257 * SIZEOF(long));
			MEMZERO(entropy->count_ptrs[tbl], 257 * SIZEOF(long));
		}
		else
		{
			/* Compute derived values for Huffman tables */
			/* We may do this more than once for a table, but it's not expensive */
			if(is_DC_band)
				jpeg_make_c_derived_tbl(cinfo, cinfo->dc_huff_tbl_ptrs[tbl], &entropy->derived_tbls[tbl]);
			else
				jpeg_make_c_derived_tbl(cinfo, cinfo->ac_huff_tbl_ptrs[tbl], &entropy->derived_tbls[tbl]);
		}
	}

	/* Initialize AC stuff */
	entropy->EOBRUN = 0;
	entropy->BE = 0;

	/* Initialize bit buffer to empty */
	entropy->put_buffer = 0;
	entropy->put_bits = 0;

	/* Initialize restart stuff */
	entropy->restarts_to_go = cinfo->restart_interval;
	entropy->next_restart_num = 0;
}


/* Outputting bytes to the file.
 * NB: these must be called only when actually outputting,
 * that is, entropy->gather_statistics == FALSE.
 */

/* Emit a byte */
#define emit_byte(entropy,val)  \
	{ *(entropy)->next_output_byte++ = (JOCTET) (val);  \
	  if (--(entropy)->free_in_buffer == 0)  \
	    dump_buffer(entropy); }


LOCAL void dump_buffer(phuff_entropy_ptr entropy)
/* Empty the output buffer; we do not support suspension in this module. */
{
	struct jpeg_destination_mgr *dest = entropy->cinfo->dest;

	if(!(*dest->empty_output_buffer) (entropy->cinfo))
		ERREXIT(entropy->cinfo, JERR_CANT_SUSPEND);
	/* After a successful buffer dump, must reset buffer pointers */
	entropy->next_output_byte = dest->next_output_byte;
	entropy->free_in_buffer = dest->free_in_buffer;
}


/* Outputting bits to the file */

/* Only the right 24 bits of put_buffer are used; the valid bits are
 * left-justified in this part.  At most 16 bits can be passed to emit_bits
 * in one call, and we never retain more than 7 bits in put_buffer
 * between calls, so 24 bits are sufficient.
 */

INLINE LOCAL void emit_bits(phuff_entropy_ptr entropy, unsigned int code, int size)
/* Emit some bits, unless we are in gather mode */
{
	/* This routine is heavily used, so it's worth coding tightly. */
	register INT32  put_buffer = (INT32) code;
	register int    put_bits = entropy->put_bits;

	/* if size is 0, caller used an invalid Huffman table entry */
	if(size == 0)
		ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);

	if(entropy->gather_statistics)
		return;					/* do nothing if we're only getting stats */

	put_buffer &= (((INT32) 1) << size) - 1;	/* mask off any extra bits in code */

	put_bits += size;			/* new number of bits in buffer */

	put_buffer <<= 24 - put_bits;	/* align incoming bits */

	put_buffer |= entropy->put_buffer;	/* and merge with old buffer contents */

	while(put_bits >= 8)
	{
		int             c = (int)((put_buffer >> 16) & 0xFF);

		emit_byte(entropy, c);
		if(c == 0xFF)
		{						/* need to stuff a zero byte? */
			emit_byte(entropy, 0);
		}
		put_buffer <<= 8;
		put_bits -= 8;
	}

	entropy->put_buffer = put_buffer;	/* update variables */
	entropy->put_bits = put_bits;
}


LOCAL void flush_bits(phuff_entropy_ptr entropy)
{
	emit_bits(entropy, 0x7F, 7);	/* fill any partial byte with ones */
	entropy->put_buffer = 0;	/* and reset bit-buffer to empty */
	entropy->put_bits = 0;
}


/*
 * Emit (or just count) a Huffman symbol.
 */

INLINE LOCAL void emit_symbol(phuff_entropy_ptr entropy, int tbl_no, int symbol)
{
	if(entropy->gather_statistics)
		entropy->count_ptrs[tbl_no][symbol]++;
	else
	{
		c_derived_tbl  *tbl = entropy->derived_tbls[tbl_no];

		emit_bits(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]);
	}
}


/*
 * Emit bits from a correction bit buffer.
 */

LOCAL void emit_buffered_bits(phuff_entropy_ptr entropy, char *bufstart, unsigned int nbits)
{
	if(entropy->gather_statistics)
		return;					/* no real work */

	while(nbits > 0)
	{
		emit_bits(entropy, (unsigned int)(*bufstart), 1);
		bufstart++;
		nbits--;
	}
}


/*
 * Emit any pending EOBRUN symbol.
 */

LOCAL void emit_eobrun(phuff_entropy_ptr entropy)
{
	register int    temp, nbits;

	if(entropy->EOBRUN > 0)
	{							/* if there is any pending EOBRUN */
		temp = entropy->EOBRUN;
		nbits = 0;
		while((temp >>= 1))
			nbits++;

		emit_symbol(entropy, entropy->ac_tbl_no, nbits << 4);
		if(nbits)
			emit_bits(entropy, entropy->EOBRUN, nbits);

		entropy->EOBRUN = 0;

		/* Emit any buffered correction bits */
		emit_buffered_bits(entropy, entropy->bit_buffer, entropy->BE);
		entropy->BE = 0;
	}
}


/*
 * Emit a restart marker & resynchronize predictions.
 */

LOCAL void emit_restart(phuff_entropy_ptr entropy, int restart_num)
{
	int             ci;

	emit_eobrun(entropy);

	if(!entropy->gather_statistics)
	{
		flush_bits(entropy);
		emit_byte(entropy, 0xFF);
		emit_byte(entropy, JPEG_RST0 + restart_num);
	}

	if(entropy->cinfo->Ss == 0)
	{
		/* Re-initialize DC predictions to 0 */
		for(ci = 0; ci < entropy->cinfo->comps_in_scan; ci++)
			entropy->last_dc_val[ci] = 0;
	}
	else
	{
		/* Re-initialize all AC-related fields to 0 */
		entropy->EOBRUN = 0;
		entropy->BE = 0;
	}
}


/*
 * MCU encoding for DC initial scan (either spectral selection,
 * or first pass of successive approximation).
 */

METHODDEF       boolean encode_mcu_DC_first(j_compress_ptr cinfo, JBLOCKROW * MCU_data)
{
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	register int    temp, temp2;
	register int    nbits;
	int             blkn, ci;
	int             Al = cinfo->Al;
	JBLOCKROW       block;
	jpeg_component_info *compptr;

	ISHIFT_TEMPS entropy->next_output_byte = cinfo->dest->next_output_byte;
	entropy->free_in_buffer = cinfo->dest->free_in_buffer;

	/* Emit restart marker if needed */
	if(cinfo->restart_interval)
		if(entropy->restarts_to_go == 0)
			emit_restart(entropy, entropy->next_restart_num);

	/* Encode the MCU data blocks */
	for(blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++)
	{
		block = MCU_data[blkn];
		ci = cinfo->MCU_membership[blkn];
		compptr = cinfo->cur_comp_info[ci];

		/* Compute the DC value after the required point transform by Al.
		 * This is simply an arithmetic right shift.
		 */
		temp2 = IRIGHT_SHIFT((int)((*block)[0]), Al);

		/* DC differences are figured on the point-transformed values. */
		temp = temp2 - entropy->last_dc_val[ci];
		entropy->last_dc_val[ci] = temp2;

		/* Encode the DC coefficient difference per section G.1.2.1 */
		temp2 = temp;
		if(temp < 0)
		{
			temp = -temp;		/* temp is abs value of input */
			/* For a negative input, want temp2 = bitwise complement of abs(input) */
			/* This code assumes we are on a two's complement machine */
			temp2--;
		}

		/* Find the number of bits needed for the magnitude of the coefficient */
		nbits = 0;
		while(temp)
		{
			nbits++;
			temp >>= 1;
		}

		/* Count/emit the Huffman-coded symbol for the number of bits */
		emit_symbol(entropy, compptr->dc_tbl_no, nbits);

		/* Emit that number of bits of the value, if positive, */
		/* or the complement of its magnitude, if negative. */
		if(nbits)				/* emit_bits rejects calls with size 0 */
			emit_bits(entropy, (unsigned int)temp2, nbits);
	}

	cinfo->dest->next_output_byte = entropy->next_output_byte;
	cinfo->dest->free_in_buffer = entropy->free_in_buffer;

	/* Update restart-interval state too */
	if(cinfo->restart_interval)
	{
		if(entropy->restarts_to_go == 0)
		{
			entropy->restarts_to_go = cinfo->restart_interval;
			entropy->next_restart_num++;
			entropy->next_restart_num &= 7;
		}
		entropy->restarts_to_go--;
	}

	return TRUE;
}


/*
 * MCU encoding for AC initial scan (either spectral selection,
 * or first pass of successive approximation).
 */

METHODDEF       boolean encode_mcu_AC_first(j_compress_ptr cinfo, JBLOCKROW * MCU_data)
{
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	register int    temp, temp2;
	register int    nbits;
	register int    r, k;
	int             Se = cinfo->Se;
	int             Al = cinfo->Al;
	JBLOCKROW       block;

	entropy->next_output_byte = cinfo->dest->next_output_byte;
	entropy->free_in_buffer = cinfo->dest->free_in_buffer;

	/* Emit restart marker if needed */
	if(cinfo->restart_interval)
		if(entropy->restarts_to_go == 0)
			emit_restart(entropy, entropy->next_restart_num);

	/* Encode the MCU data block */
	block = MCU_data[0];

	/* Encode the AC coefficients per section G.1.2.2, fig. G.3 */

	r = 0;						/* r = run length of zeros */

	for(k = cinfo->Ss; k <= Se; k++)
	{
		if((temp = (*block)[jpeg_natural_order[k]]) == 0)
		{
			r++;
			continue;
		}
		/* We must apply the point transform by Al.  For AC coefficients this
		 * is an integer division with rounding towards 0.  To do this portably
		 * in C, we shift after obtaining the absolute value; so the code is
		 * interwoven with finding the abs value (temp) and output bits (temp2).
		 */
		if(temp < 0)
		{
			temp = -temp;		/* temp is abs value of input */
			temp >>= Al;		/* apply the point transform */
			/* For a negative coef, want temp2 = bitwise complement of abs(coef) */
			temp2 = ~temp;
		}
		else
		{
			temp >>= Al;		/* apply the point transform */
			temp2 = temp;
		}
		/* Watch out for case that nonzero coef is zero after point transform */
		if(temp == 0)
		{
			r++;
			continue;
		}

		/* Emit any pending EOBRUN */
		if(entropy->EOBRUN > 0)
			emit_eobrun(entropy);
		/* if run length > 15, must emit special run-length-16 codes (0xF0) */
		while(r > 15)
		{
			emit_symbol(entropy, entropy->ac_tbl_no, 0xF0);
			r -= 16;
		}

		/* Find the number of bits needed for the magnitude of the coefficient */
		nbits = 1;				/* there must be at least one 1 bit */
		while((temp >>= 1))
			nbits++;

		/* Count/emit Huffman symbol for run length / number of bits */
		emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + nbits);

		/* Emit that number of bits of the value, if positive, */
		/* or the complement of its magnitude, if negative. */
		emit_bits(entropy, (unsigned int)temp2, nbits);

		r = 0;					/* reset zero run length */
	}

	if(r > 0)
	{							/* If there are trailing zeroes, */
		entropy->EOBRUN++;		/* count an EOB */
		if(entropy->EOBRUN == 0x7FFF)
			emit_eobrun(entropy);	/* force it out to avoid overflow */
	}

	cinfo->dest->next_output_byte = entropy->next_output_byte;
	cinfo->dest->free_in_buffer = entropy->free_in_buffer;

	/* Update restart-interval state too */
	if(cinfo->restart_interval)
	{
		if(entropy->restarts_to_go == 0)
		{
			entropy->restarts_to_go = cinfo->restart_interval;
			entropy->next_restart_num++;
			entropy->next_restart_num &= 7;
		}
		entropy->restarts_to_go--;
	}

	return TRUE;
}


/*
 * MCU encoding for DC successive approximation refinement scan.
 * Note: we assume such scans can be multi-component, although the spec
 * is not very clear on the point.
 */

METHODDEF       boolean encode_mcu_DC_refine(j_compress_ptr cinfo, JBLOCKROW * MCU_data)
{
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	register int    temp;
	int             blkn;
	int             Al = cinfo->Al;
	JBLOCKROW       block;

	entropy->next_output_byte = cinfo->dest->next_output_byte;
	entropy->free_in_buffer = cinfo->dest->free_in_buffer;

	/* Emit restart marker if needed */
	if(cinfo->restart_interval)
		if(entropy->restarts_to_go == 0)
			emit_restart(entropy, entropy->next_restart_num);

	/* Encode the MCU data blocks */
	for(blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++)
	{
		block = MCU_data[blkn];

		/* We simply emit the Al'th bit of the DC coefficient value. */
		temp = (*block)[0];
		emit_bits(entropy, (unsigned int)(temp >> Al), 1);
	}

	cinfo->dest->next_output_byte = entropy->next_output_byte;
	cinfo->dest->free_in_buffer = entropy->free_in_buffer;

	/* Update restart-interval state too */
	if(cinfo->restart_interval)
	{
		if(entropy->restarts_to_go == 0)
		{
			entropy->restarts_to_go = cinfo->restart_interval;
			entropy->next_restart_num++;
			entropy->next_restart_num &= 7;
		}
		entropy->restarts_to_go--;
	}

	return TRUE;
}


/*
 * MCU encoding for AC successive approximation refinement scan.
 */

METHODDEF       boolean encode_mcu_AC_refine(j_compress_ptr cinfo, JBLOCKROW * MCU_data)
{
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	register int    temp;
	register int    r, k;
	int             EOB;
	char           *BR_buffer;
	unsigned int    BR;
	int             Se = cinfo->Se;
	int             Al = cinfo->Al;
	JBLOCKROW       block;
	int             absvalues[DCTSIZE2];

	entropy->next_output_byte = cinfo->dest->next_output_byte;
	entropy->free_in_buffer = cinfo->dest->free_in_buffer;

	/* Emit restart marker if needed */
	if(cinfo->restart_interval)
		if(entropy->restarts_to_go == 0)
			emit_restart(entropy, entropy->next_restart_num);

	/* Encode the MCU data block */
	block = MCU_data[0];

	/* It is convenient to make a pre-pass to determine the transformed
	 * coefficients' absolute values and the EOB position.
	 */
	EOB = 0;
	for(k = cinfo->Ss; k <= Se; k++)
	{
		temp = (*block)[jpeg_natural_order[k]];
		/* We must apply the point transform by Al.  For AC coefficients this
		 * is an integer division with rounding towards 0.  To do this portably
		 * in C, we shift after obtaining the absolute value.
		 */
		if(temp < 0)
			temp = -temp;		/* temp is abs value of input */
		temp >>= Al;			/* apply the point transform */
		absvalues[k] = temp;	/* save abs value for main pass */
		if(temp == 1)
			EOB = k;			/* EOB = index of last newly-nonzero coef */
	}

	/* Encode the AC coefficients per section G.1.2.3, fig. G.7 */

	r = 0;						/* r = run length of zeros */
	BR = 0;						/* BR = count of buffered bits added now */
	BR_buffer = entropy->bit_buffer + entropy->BE;	/* Append bits to buffer */

	for(k = cinfo->Ss; k <= Se; k++)
	{
		if((temp = absvalues[k]) == 0)
		{
			r++;
			continue;
		}

		/* Emit any required ZRLs, but not if they can be folded into EOB */
		while(r > 15 && k <= EOB)
		{
			/* emit any pending EOBRUN and the BE correction bits */
			emit_eobrun(entropy);
			/* Emit ZRL */
			emit_symbol(entropy, entropy->ac_tbl_no, 0xF0);
			r -= 16;
			/* Emit buffered correction bits that must be associated with ZRL */
			emit_buffered_bits(entropy, BR_buffer, BR);
			BR_buffer = entropy->bit_buffer;	/* BE bits are gone now */
			BR = 0;
		}

		/* If the coef was previously nonzero, it only needs a correction bit.
		 * NOTE: a straight translation of the spec's figure G.7 would suggest
		 * that we also need to test r > 15.  But if r > 15, we can only get here
		 * if k > EOB, which implies that this coefficient is not 1.
		 */
		if(temp > 1)
		{
			/* The correction bit is the next bit of the absolute value. */
			BR_buffer[BR++] = (char)(temp & 1);
			continue;
		}

		/* Emit any pending EOBRUN and the BE correction bits */
		emit_eobrun(entropy);

		/* Count/emit Huffman symbol for run length / number of bits */
		emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + 1);

		/* Emit output bit for newly-nonzero coef */
		temp = ((*block)[jpeg_natural_order[k]] < 0) ? 0 : 1;
		emit_bits(entropy, (unsigned int)temp, 1);

		/* Emit buffered correction bits that must be associated with this code */
		emit_buffered_bits(entropy, BR_buffer, BR);
		BR_buffer = entropy->bit_buffer;	/* BE bits are gone now */
		BR = 0;
		r = 0;					/* reset zero run length */
	}

	if(r > 0 || BR > 0)
	{							/* If there are trailing zeroes, */
		entropy->EOBRUN++;		/* count an EOB */
		entropy->BE += BR;		/* concat my correction bits to older ones */
		/* We force out the EOB if we risk either:
		 * 1. overflow of the EOB counter;
		 * 2. overflow of the correction bit buffer during the next MCU.
		 */
		if(entropy->EOBRUN == 0x7FFF || entropy->BE > (MAX_CORR_BITS - DCTSIZE2 + 1))
			emit_eobrun(entropy);
	}

	cinfo->dest->next_output_byte = entropy->next_output_byte;
	cinfo->dest->free_in_buffer = entropy->free_in_buffer;

	/* Update restart-interval state too */
	if(cinfo->restart_interval)
	{
		if(entropy->restarts_to_go == 0)
		{
			entropy->restarts_to_go = cinfo->restart_interval;
			entropy->next_restart_num++;
			entropy->next_restart_num &= 7;
		}
		entropy->restarts_to_go--;
	}

	return TRUE;
}


/*
 * Finish up at the end of a Huffman-compressed progressive scan.
 */

METHODDEF void finish_pass_phuff(j_compress_ptr cinfo)
{
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;

	entropy->next_output_byte = cinfo->dest->next_output_byte;
	entropy->free_in_buffer = cinfo->dest->free_in_buffer;

	/* Flush out any buffered data */
	emit_eobrun(entropy);
	flush_bits(entropy);

	cinfo->dest->next_output_byte = entropy->next_output_byte;
	cinfo->dest->free_in_buffer = entropy->free_in_buffer;
}


/*
 * Finish up a statistics-gathering pass and create the new Huffman tables.
 */

METHODDEF void finish_pass_gather_phuff(j_compress_ptr cinfo)
{
	phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
	boolean         is_DC_band;
	int             ci, tbl;
	jpeg_component_info *compptr;
	JHUFF_TBL     **htblptr;
	boolean         did[NUM_HUFF_TBLS];

	/* Flush out buffered data (all we care about is counting the EOB symbol) */
	emit_eobrun(entropy);

	is_DC_band = (cinfo->Ss == 0);

	/* It's important not to apply jpeg_gen_optimal_table more than once
	 * per table, because it clobbers the input frequency counts!
	 */
	MEMZERO(did, SIZEOF(did));

	for(ci = 0; ci < cinfo->comps_in_scan; ci++)
	{
		compptr = cinfo->cur_comp_info[ci];
		if(is_DC_band)
		{
			if(cinfo->Ah != 0)	/* DC refinement needs no table */
				continue;
			tbl = compptr->dc_tbl_no;
		}
		else
		{
			tbl = compptr->ac_tbl_no;
		}
		if(!did[tbl])
		{
			if(is_DC_band)
				htblptr = &cinfo->dc_huff_tbl_ptrs[tbl];
			else
				htblptr = &cinfo->ac_huff_tbl_ptrs[tbl];
			if(*htblptr == NULL)
				*htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
			jpeg_gen_optimal_table(cinfo, *htblptr, entropy->count_ptrs[tbl]);
			did[tbl] = TRUE;
		}
	}
}


/*
 * Module initialization routine for progressive Huffman entropy encoding.
 */

GLOBAL void jinit_phuff_encoder(j_compress_ptr cinfo)
{
	phuff_entropy_ptr entropy;
	int             i;

	entropy = (phuff_entropy_ptr) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(phuff_entropy_encoder));
	cinfo->entropy = (struct jpeg_entropy_encoder *)entropy;
	entropy->pub.start_pass = start_pass_phuff;

	/* Mark tables unallocated */
	for(i = 0; i < NUM_HUFF_TBLS; i++)
	{
		entropy->derived_tbls[i] = NULL;
		entropy->count_ptrs[i] = NULL;
	}
	entropy->bit_buffer = NULL;	/* needed only in AC refinement scan */
}

#endif							/* C_PROGRESSIVE_SUPPORTED */
